Method for temporarily increasing the resistance to vertical compression of a bag for transporting and holding liquids and quasi-liquids, and resulting bag

ABSTRACT

The invention relates to a method for temporarily increasing the resistance to vertical compression of a bag for transporting and holding liquids and quasi-liquids, intended for a bag having the general shape of a cube and including receptacles of each of the corners thereof. The method consists in choosing four inflatable cushioning pouches for each bag, said pouches being elongate and having length, width and extension dimensions corresponding to the length, width and internal volume of the receptacles in the bag. Next, the four cushioning pouches are introduced into the four receptacles and are subsequently inflated, thereby trapping same in a vertical position in which they can resist compression along the vertical axis thereof. The resulting bag is characterized in that the receptacles in the four corners of the bag are each provided internally with a cushioning pouch which is optionally rigidly secured to the bag.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to International Application No. PCT/IB2012/050208, filed Jan. 17, 201.2, which claims the benefit of Swiss Application No. 00093/11 filed Jan. 19, 2011, the contents of which are hereby incorporated by reference herein.

FIELD OF INVENTION

The invention relates to a method of temporarily increasing the vertical resistance to compression of a bag for conveying and handling liquid or quasi-liquid substances. It also relates to a bag obtained by the method.

BACKGROUND

Industrial-scale transport of liquid and quasi-liquid substances, particularly concentrated fruit juice, for example, is an important branch of global commerce. To convey such substances, the first idea that conies to mind is to place them in rigid containers such as tanks with metal or plastic walls.

Such rigid containers, however, have a serious disadvantage, namely they take up the same space when empty as when full. Conveying empty containers over very long distances in order to return them to the filling point is economically and ecologically absurd. For this reason the natural preference, when available, will be for flexible containers which can be unfolded for filling or folded up to the minimum volume during the return journey to the filling place.

A flexible container of this kind is known in particular from document WO 2009/010928 A2, which basically discloses an external envelope made up of sections of cloth, assembled and forming a roughly cubic bag containing a second envelope or liner for filling with a liquid or quasi-liquid substance. The four sides of the outer envelope are made of backed cloth and divided into compartments for receiving reinforcing plates. The four vertical edges of the bag forming the outer envelope are separated from the liner by strips of cloth sewn vertically and parallel to the said edges in order to counteract the tendency of the bag when filled to bulge outwardly under the pressure of the liquid it contains.

A special feature of trade in liquid or quasi-liquid substances, particularly concentrated fruit juice, is that the quantity of liquid actually conveyed in a container rarely depends on the maximum internal volume thereof. The container is not filled up to the brim but in dependence on the order, or the volume of liquid available in the vat for emptying. For this reason, containers (flexible or otherwise) in transmit are usually filled only partly, not to full capacity.

Rigid containers have disadvantages as mentioned, but they have one advantage over flexible containers, in that even when partly filled they can be superposed by stacking two or three on one another.

Stacking of flexible containers, particularly when partly filled, therefore presents a problem, which hitherto has been solved by using wooden cases in which the flexible containers are placed for conveyance. Since the weight of such a case may be up to 100 kg per container, a considerable saving in every respect can be made by eliminating it.

SUMMARY

The aim of the invention is temporarily to increase the resistance to vertical compression of a bag for conveying and handling liquid or quasi-liquid substances so that the bags can be stacked, thus eliminating the need to use cases for this sole purpose.

To this end, the process for temporarily increasing the resistance to vertical compression of a bag for conveying and handling liquids and quasi-liquids, the bag comprising a liner and receptacles, is characterised in that inflatable wedging cushions are chosen for each bag, the cushions being elongated and having a length, width and spread related to the length, width and internal volume of the bag receptacles, and in that the wedging cushions are inserted into the receptacles in order subsequently to inflate the cushions and thus confine them in a vertical position enabling them to resist compression along their vertical axes. Another aim of the invention is to provide a bag by the method, a special feature of which is that the receptacles at the corners of the bag are each provided with an internal wedging cushion secured to the bag if required.

According to an embodiment, the bag is substantially cubic and has receptacles at each corner. The bag can have four receptacles, one at each corner of the bag.

According to an embodiment, four wedging cushions are chosen for each bag.

According to an embodiment, at least one wedging bag is inserted per receptacle.

According to an embodiment, the wedging cushions each comprise two welded-together films, e.g. of polythene, and an inflating and deflating valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description refers to the drawing, in which FIG. 1 is a partly exploded perspective view illustrating use of the method according to the invention.

FIG. 1 shows a bag for conveying and handling liquid or quasi-liquid substances constructed as taught in document WO 2009/010928.

DETAILED DESCRIPTION

A bag 1 has four sides made of backed cloth. Each side of the bag has three sections bounded by two vertical seams, in which a reinforcing panel 2 can be seen, inserted between the two pieces of cloth for each of the three sections.

As can be seen, the four corners of the bag comprise receptacles 3 forming triangular-section parallelpipeds, and the upper mouths of the four receptacles are free, not closed.

The spaces constituted by the four receptacles can be filled with any components needed for stacking the bags. Note that each bag interior, its central part, is occupied by a liner for filling with the liquid for conveyance.

Of course, additional frames, such as loops or cores of suitable size, can be inserted into the resists, but it is much more elegant to obtain the desired result without increasing the total conveyed weight.

In the world of transport, particularly in harbours, use is made of inflatable wedging cushions (dunnage bags) for stabilising loads, e.g. inside large 40-foot ISO containers. These cushions, when deflated, look like empty flat pillowcases. The cushions are made from two polyethylene films welded together over their entire periphery and comprise an inflating and deflating valve. When inflated with compressed air, the cushions look like large, particularly plumped-up pillows.

Various sizes and shapes of said inflatable cushions are commercially available.

These cushions are very strong, and can be made as hard as stone by sufficiently high internal pressure.

In all normal applications, the cushions are used for laterally filling the space between two loads so as to keep them apart along a horizontal axis determined by the centres of the two sides of the cushion. On the other hand there is no advantage—quite the contrary—in using the properties of these cushions along a different axis.

This however is the idea which is the key to the process according to the invention.

As shown in FIG. 1, the chosen wedging cushion 4 has dimensions corresponding to the height and width of the receptacles 3. The cushion is also chosen in dependence on the position of the inflating valve 5, which should be near a longitudinal end of the cushion.

Four cushions are used for each bag and each is inserted, when deflated, into one of the resists 3.

Once the liner has been filled with the quantity of liquid for transportation, the four fastening cushions are inflated with compressed air.

Inflation inside the resists 3 has a double effect. Firstly the pressure applied to the inner faces of the receptacles increases the tension on the cloth and helps to lock the reinforcing panels 2 in position. This first effect has an immediately beneficial result, i.e. that optimum rigidity of the entire bag structure is guaranteed even if the liner is only partly filled with liquid. However this interaction between the bag structure and the cushions has a second effect, i.e. of confining each cushion in the only position permitted by the bag structure or the orientation of the receptacles 3, i.e. an overall vertical position. Wedged in its corset, each cushion can offer high resistance to vertical forces, which could not have been foreseen. This applies particularly to the vertical forces generated by the weight of one or more other bags filled and stacked on the first. The two effects are present and really independent, and it is difficult to credit either separately with another advantage, i.e. that the optimum rigidity of the bag structure and its higher resistance to vertical compression are not affected if a damaged liner loses its contents. The stability and rigidity of the bag are undoubtedly better when the liner is at least partly filled with liquid, but the operating threshold enabling bags to be stacked is obtained by the method according to the invention even if the liner is empty.

To avoid having to apply the process more than once for each bag, the inflatable cushions can be secured, permanently or otherwise, in the bag resists and kept there during inflation and deflation, e.g. by a carrying strap or a holding lug which prevents the bag when deflated from coming out of its resistance.

The advantages of the method according to the invention are, firstly, a benefit during the journey from the filling place to the destination, and secondly during the return journey.

During the first journey, without any increase in weight, since the weight of the cushions is insignificant, the filled bags can be stacked on one another and of course other loads can be placed on one or more filled bags.

During the second journey the deflated bag has a relatively insignificant volume and practically zero weight as stated.

Finally the cost of a bag of the chosen kind is also practically zero and does not significantly increase the cost of conveyance, and judicious use according to the invention can result in substantial savings in weight and in volume conveyed. 

1. A method of temporarily increasing the resistance to vertical compression of a bag for conveying and handling liquids and quasi-liquids, the bag comprising a liner and receptacles, the method comprising: choosing inflatable wedging cushions for the bag, the cushions being elongated and having a length, width and spread related to the length, width and internal volume of the bag receptacles; and inserting the wedging cushions into the receptacles in order subsequently to inflate the cushions and thus confine them in a vertical position enabling them to resist compression along their vertical axes.
 2. The method according to claim 1 wherein the wedging cushions are inflated in the receptacles after having introduced the quantity of liquid for conveyance into the liner.
 3. The method according to claim 1 wherein the bag has a generally cubic shape and has four receptacles at its corners for inserting at least one wedging cushion.
 4. A bag, comprising a liner, receptacles, and an internal wedging cushion located in each of the receptacles and secured to the bag, the internal wedging cushions being inflatable, and wherein the inflatable wedging cushions have a length, width and spread related to the length, width and internal volume of the bag receptacles, and wherein the internal wedging cushions are inserted into the receptacles in order subsequently to inflate the cushions and thus confine them in a vertical position enabling them to resist compression along their vertical axes.
 5. The bag according to claim 4 wherein the bag has a generally cubic shape and further comprises four receptacles, wherein one of the four receptacles is located at each corner of the bag.
 6. The bag according to claim 4 wherein the internal wedging cushions each comprise two welded-together polyethylene films and an inflating/deflating valve. 